Rename helpers for a few controls to conform to the more prevelant style
of cpu_has_vmx_<feature>().  Consistent names will allow adding macros
to consolidate the boilerplate code for adjusting secondary execution
controls.

No functional change intended.
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200923165048.20486-2-sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>